TI-BASIC is a strongly and dynamically-typed language
Variables are global. There is no local variables. So programs cannot be recursive, even if a program can call itself.

Numerical variables, 27 variables from A to Z and theta. These allow real numbers or complex numbers (implemented as pairs of reals) to be stored in floating point format. Values may range from 1E-99 to 1E99 with up to ten digits of accuracy.

Strings, 10 strings from Str1 to Str9 and Str0.

Lists, including L1 - L6, with the ability to create additional ones. These are essentially one-dimensional arrays used to store a real or complex number into each of their elements. (L1(4) would return the value of L1 at n=4)

Matrices, 8 matrices from [A] to [J]. Their elements are subject to the same restrictions as lists. Their dimensions may be defined up to 99x99 elements, although, again, available memory will limit this. ([A](3,4) would design item at row=3 column=4)